<!DOCTYPE html>
<html>

<head>
    <meta charset="utf-8">
    <script>
        function loadXMLDoc() {
            var xmlhttp;
            if (window.XMLHttpRequest) {
                //  IE7+, Firefox, Chrome, Opera, Safari 浏览器执行代码
                xmlhttp = new XMLHttpRequest();
            } else {
                // IE6, IE5 浏览器执行代码
                xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
            }
            xmlhttp.open("GET", "/try/ajax/ajax_info.txt", true);
            xmlhttp.onreadystatechange = function() {
                if (xmlhttp.readyState == 4 && xmlhttp.status == 200) {
                    document.getElementById("myDiv").innerHTML = xmlhttp.responseText;
                }
            }

            xmlhttp.send();
        }
    </script>
</head>

<body>

    <div id="myDiv">
        <h2>使用 AJAX 修改该文本内容</h2>
    </div>
    <button type="button" onclick="loadXMLDoc()">修改内容</button>

</body>

</html>